Locker excluded
I know fo example blackstone labs does not feel synthetic performs better than conventional when looking at wear numbers.
But with gear oil there is the group that believes conventional is better than synthetic and I have never understood. Anybody know why they may think this?
I can see thicker oil‘s climbing better and staying with gears better but that’s also negative effect in the cold climates and we know that thicker oil’s resist heat better but once they’re hot it’s much harder to dispense the heat. Thinner oils heat up much faster but dispense heat much faster.
So why do some think conventional gear oil is better ?
Thoughts?
Old formula compatibility issues that are long since solved.
Synthetics are clearly superior in the extreme zone where temperatures, high loads or flammability are overriding factors. They also perform well in applications where needs are specific and complex. Synthetics are engineered to meet targeted performance benchmarks, and a synthetic formula can be (and probably has been) engineered for almost every combination of properties used in industry.
That was machibelube's take.
Mineral Oils
Many factors differentiate mineral oils from synthetic lubricants including what they can accomplish, their requirements for efficient functionality, and composition.
Naturally occurring crude is a cocktail of hydrocarbons. Even after aggressive solvent-based refining, thousands of hydrocarbon compounds - as well as organic compounds of oxygen, sulfur and nitrogen - remain.
These three compounds in particular are problematic because they enable oxidation and acid development, as well as facilitate the formation of sludge, particularly in high-temperature applications.
The varying molecules of refined lubricants also have differing shapes, resulting in irregular lubricant surfaces at the molecular level. These irregularities generate friction within the fluid itself which increases power requirements and reduces efficiency.
Gear Wear
The issue of gear wear is also a consideration. A study cited in
Machinery Lubrication magazine1 implied synthetic lubricants make gears more efficient than mineral oils. A polyglycol showed the highest efficiency (18 percent more than the high-performing mineral oil).
Synthetic hydrocarbon (SHC) gear oil also increased the efficiency of the best gears by eight to nine percent. The performance of synthetic lubricants in food-grade applications in accordance with USDA-H1 food contact is also a benefit. Food-grade synthetics are sometimes believed to be inferior in performance to mineral oil lubes, a belief the study dispels.
Service Life
A popular topic concerning the difference between mineral oils and synthetic lubricants is service life. Synthetic lubricants as a class don't show their age, particularly at high temperatures, and have a longer service life.
Often, the change interval is several times longer for synthetics at identical operating temperatures; however, the exact number depends on operating conditions, the additives and the specific synthetic used.
Synthetic lubricants have a lower friction coefficient in a gearbox, better film strength and a better relationship between viscosity and temperature (viscosity index, VI). This indicates synthetic lubricants can be used at lower viscosity grades and lower temperatures. When this is the case, the gap between the service lives of minerals and synthetics significantly increases.
Related to the oil change interval is the issue of product loss through evaporation and disposal. Both sludge and residue form more readily with mineral oil products. Evaporative losses are lower for synthetics due to the lack of lighter hydrocarbon structures.
Disposal is more costly with some synthetics, but it is nowhere near enough to compensate for change-out intervals that are three to five times more frequent.